Preheat oven to 400ºF. Line baking sheet with parchment paper (or leave ungreased).
In a large bowl, combine flour, baking powder and salt. Toss in butter cubes, and use a pastry cutter or your fingers to work the butter into the flour mixture until the pieces are about the size of lentils (it's ok if there are a few bigger ones). Add the buttermilk and use a gentle hand to stir it in with a rubber spatula, scraping from the bottom of the bowl and folding over, only just until no more dry patches remain and then stop (over-mixing results in tough biscuits).
Drop by large spoonfuls (approximately 1/3 cup per biscuit) onto baking sheet. Bake for about 15 minutes, or until golden brown. The top should spring back when gently pressed in the centre. Cool on wire racks.
While biscuits are baking, combine strawberries and sugar in a medium bowl. Let stand at room temperature until they are nice and juicy, about 30 minutes. Lightly mash with a fork or potato masher, if desired.
Whip cream to soft peaks with an electric mixer, then beat in sugar and vanilla extract. Just before serving, slice biscuits in half, top the bottom with strawberries and whipped cream, then place the second half of biscuit on top. (You can add more strawberries and whipped cream to the top, too, if you wish...). Serve immediately. Store any extra biscuits in a sealed container at room temperature (or in the freezer) and any extra berry sauce and whipped cream covered in the fridge.